28989135 Stealth Technology Ppt

Stealth Technology

ByAkshay Rai

Outline What is stealth? Why? How? Where? Advantages Disadvantages Going Ahead

History of stealth Second World War

German initiation

Radar Absorbent paint

Have Blue Program

What? LO Tech

Passive electronic countermeasure

Less Invisible to RADAR, SONAR, IR

Why?

Deter Detection

Reduction of Casualties

How? Concept of Signature and it s types

Concept of RADAR

Concept of RCS(Radar Cross section)

Visual Stealth and Acoustic stealth

Concept of IR Stealth

What is radar?

Principles of radar Echo Echo can be

considered as a wave bouncing off the surface and coming back to source.

This principle can be used to detect time and distance of target .

Doppler shift This is second

principle of radar. This can b used to

detect the speed of target approaching..

Radar Cross Section(RCS ) Radar cross section is the measure of a

targets ability to reflect radar signals

The conceptual definition of RCS includes the fact that not all of the radiating energy falls on the target .

RADIATION SCATTERING BY TARGET

•The sphere is essentially same in almost all directions i.e. 360 degree

•The flat plane has has almost no rcs except when aligned directly towards radar i.e. 90 degree

•The corner reflector has an rcs almost high as flat plane over a wider angle i.e. 60 degree.

Minimizing RCS

Conventional aircraft use round shape cone as it support principle of aerodynamics.

The stealth aircraft is made up of flat surface and very sharp edges

Radar signal heating the stealth plane are scattered in all directions by this.

Metallic surfaces generally reflect the radar signals.

There stealth aircraft should be coated with radar absorbent materials.

Which deflect and absorbed incoming radar waves and reduce the detection range.

Radar absorbent layer is present below the surface coating of aircraft using corner reflector.

GEOMETRIC DESIGN RADAR ABSORBENT MATERIALS

Minimizing RCSGEOMETRIC DESIGN RADAR ABSORBENT

MATERIALS

Visual stealth Low visibility is desirable for all military

applications Earlier stealth aircraft were painted black

and thus could be used during nights Now days an electro chromic polymer is

being developed for daytime stealth These polymer sheets sense nature of

the surrounding and change there color accordingly

Visual stealth

Acoustic stealth Acoustic cells involves the sound waves

to detect the target Knowing the fact that’s sound waves

moves too slowly as compared to radio wave so it functionality should be directed towards low altitude flying aircraft and pre-dominantly ships and submarines

Detection of submarines using acoustic stealth Thermo cline is a layer of water where the

temperature gradient is less then the surface and more then the depth.

Submarines generally move below thermo cline layer which makes almost difficult for sonar to detect it as sound waves get scattered towards depth

if the surface ship wishes to detect a submarine then the ships has to be fitted with towed sonar

Infra-Red stealth Infra-red radiation are emitted by all

matter above absolute temperature zero Hot zones such as engine exhaust , wing

surface [ friction due to air ] get heated which rather increases the visibility

These part should be kept cool as possible it can be ,

Option would be mixing of cool air with the hot engine exhaust

Infra-Red stealth

Detection of submarines using acoustic stealth

Where? Aircraft

Submarines

Advantages of Stealth tech Reduces Casualties

Saving military budget

Disadvantages of Stealth Tech Stealth aircraft cannot fly as fast as

conventional aircraft Can carry limited amount of load Expensive B-2 cost [ $2 billion ] ,F-22

[$100 million ]

Going Ahead-Plasma stealthIn this stealth the aircraft injects a stream of ionized gas which envelopes the aircraft due to which most of the radar wave are observe this make the aircraft completely invisible

Questions?????????

Thank you….